Recently, information processing devices has rapidly improved to have various designs, various functions, and more rapid speed in processing information. A display device is an interface to convert electrical information signal to visually recognizable optical information signal in these information processing devices.
These days, a liquid crystal display (LCD) device has developed and has many profit functions such as light weight, small size, full-color, high resolution, etc., in comparison with a cathode ray tube (CRT) display device. Generally, the LCD device converts a specific molecular arrangement of liquid crystal to another molecular arrangement by applying a voltage thereto, and displays an image by visually converting the changes of optical characteristics, such as double refraction, optical rotatory polarization, a dichroism and light scattering, etc.
FIG. 1 is an exploded perspective view schematically illustrating the conventional LCD, FIG. 2 and FIG. 3 are sectional views illustrating the structure of the LCD in FIG. 1, and FIG. 4 is a sectional view illustrating the bonding structure of the LCD in FIG. 1.
Referring to FIG. 1, the related LCD 100 includes a liquid crystal display module 130 for displaying an image by applying image information signal, a front case 110 and a rear case 120 for receiving the liquid crystal display module 130. The liquid crystal display module 130 includes a display unit 170 and a back light assembly 150 for providing light to the display unit 170.
The display unit 170 has a liquid crystal display panel 171, a data and a gate printed circuit board (PCB) 176 and 175, and a data and a gate tape carrier package (TCP) 178 and 174.
The liquid crystal display panel 171 includes a thin film transistor (TFT) substrate 172, a color filter substrate 173 and liquid crystal (not shown in FIG. 1).
The TFT substrate 172 is a transparent glass substrate and thin film transistors are arranged in a matrix shape on the TFT substrate 172. A data line and a gate line are connected to a source and gate terminal of the thin film transistor, respectively, and a pixel electrode made of indium tin oxide (ITO), which is transparent and conductive, is formed at a drain terminal of the thin film transistor.
The color filter substrate 173 is disposed opposite to the TFT substrate 172. The color filter substrate has RGB pixels formed by thin film process, as a color pixel. Common electrodes made of ITO are formed on the surface of the color filter substrate 173.
When a predetermined voltage of electric power is applied to the gate and source terminal of the transistor of the TFT substrate 172 and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode of the color filter substrate. The arrangement angle of the liquid crystal interposed between the TFT substrate 172 and the color filter substrate 173 is changed by this electric field, and each pixel can have a required color since the transmissivity of the light varies according to the varied arrangement angle of the liquid crystal. A driving signal and a timing signal are applied respectively to the gate line and the data line connected with the TFT in order to control the arrangement angle and the arrangement period of the liquid crystal in the liquid crystal display panel 171.
The back light assembly 150 is disposed under the display unit 170 to provide uniform light to the display unit 170. The back light assembly 150 includes lamp units 161 and 162 located at both sides of the liquid crystal display module 130 to emit a light, a light guide plate (LGP) 152 for guiding the light toward the display unit 170 and for changing the path of the light, a plurality of optical sheets 153 for making a uniform brightness of the light emitted from the LGP 152, and a reflection plate 154 disposed under the LGP 152 and reflecting the light leaking from the LGP 152 toward the LGP 152 again to improve the effectiveness of the light.
The back light assembly 150 is received in a mold frame 132 having a bottom chassis 134 therein. Also, the display unit 170 is disposed in the mold frame 132. A top chassis 140 is coupled with the mold frame 132 to correspond to the mold frame 132 in order to prevent the display unit 170 from being separated from the mold frame 132.
Then, a bracket 136 is disposed to correspond to an extended sidewall of the top chassis 140 and is received on the rear surface of the mold frame 132. Also, a shield case 138 is mounted on the rear surface of the bottom chassis 134, cuts off electromagnetic wave from an inverter circuit (not shown), and provides electric power to the display unit 170, etc. After that, the front case 110 and the rear case 120 are coupled opposite to each other to finish the assembly of the LCD.
A first engagement hole 137a and a second engagement hole 137b are formed at both the sidewalls of the bracket 136 and the top chassis 140. The number of the engagement holes is variable according to the design of the LCD device. A first screw 136a is coupled with the first engagement hole 137A to fix the bracket 136 and the top chassis 140.
On the other hand, as shown in FIG. 4, a third engagement hole 137c passing through the front cases 110 and the rear case 120 is formed at both the sidewalls of the front case 110 and the rear case 120, the third engagement hole 137c corresponding to the second engagement hole 137b. The front and rear case 110 and 120 are coupled with the liquid crystal module 130 by means of the second screw 139 coupled with the second and third engagement hole 137b and 137c. Also, a burring A (refer to FIG. 3) is formed at the bracket 136 where the second engagement hole 137b is formed, so that the second screw 139 is coupled firmly with the second and third engagement hole 137b and 137c. 
However, this LCD has the following disadvantages.
First, the bracket 136 is necessary to form the burring A for the first and second engagement hole 137A and 137b which are used to couple the front and rear case 110 and 120 with the liquid crystal display module 130. Therefore, the number of parts of the LCD 100 increases, and the cost for producing the LCD also increases.
Second, in order to assemble the LCD, the bracket 136 should be coupled with the sidewall of the mold frame 132, the shield case 138 should be fixed on the rear surface of the bottom chassis 134, and the front and rear case 110 and 120 should be coupled with the liquid crystal display module 130. Therefore, the number of processes for assembling the LCD increases and the productivity of the LCD wholly decreases.